Fuse plug



C. RIPPE FUSE PLUG Sept. 3, 1929.

Filed June 23, 1927 awwewcoz:

CHARLES R/PFE 235 1 4 a Q-ttmm QKQ/ Patented Sept. 3, 1929. i UNITED STATES PATENT OFFICE.

7 CHARLES RIPPE, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO THE BRYANT ELEC- TRIO COMPANY, OF BBIDGEPORT, CONNECTICUT, A CORPORATION OF CONNECTI- CUT.

FUSE PLUG.

Application filed June 23, 1927. Serial No. 200,937.

My invention relates to fuse plugs, and visible over its full transverse extent. The my object is to provide a construction which strip has off-set legs 20, 21 extending into the not only so locates the rupture point of the wells 17, 18 respectively. The leg 20 has its fuse that its integrity can be readily ascerend slightly bowed at 20 to engage the shoultained, but also minimizes the extent of the der formed by the opening of well17 through 60 fuse strip volatilized by the are on rupture, the body wall. By this the fuse strip is held and causes the current to follow a path which in place before the metal 22 is flowed in. The is inimical to the establishment of an are beshorter leg 20, entering the well 17, is metween the plug contacts. chanically and electrically connected to the In the accompanying drawings screw shell 7 by metal 22 flowed into the well 65 Fig. 1 is a plan view of a fuse plug in which 17. The longer leg 21 passing down through my invention is embodied in one form; and the well 18 and the lower portion of the cham- Figs. 2 and 3 are sections on the lines 22 her 2, is mechanically and electrically conand 3-3, Fig. 1, respectively. nected to the center contact at by metal 23 in- The insulating body 1 of the plug is thimtroduced through the chamber. 70 ble shape-d, affording a central chamber 2 of It will be noted that the portion of the fuse relatively large capacity, in which the metalstrip in which the calibrating recess 2a is lic gases, formed on rupture of the fuse strlp formed, is located at the head of the plug and 3, may expand without danger of injury to hes ad acent and substantially parallel to the the fuse plug. At the bottom of the chamber transparent diaphragm 11 through which 75 is a central aperture in the end web of the lnlt may be readily inspected to ascertain sulating body, at which the center contact 4: Whether or not the strip has been ruptured. of the plug is secured by means of lugs 5 The legs 20 and 21 of the fuse strip, on the which pass through the aperture and are upother hand, offset at shar angles to the caliset within the chamber. brated portion of the strip, extend into wells so On the exterior of the plug body is molded formed in the insulating body.

a spiral rib 6, which is engaged by the threads On the blowing of the fuse, the strip rupof a screw shell side contact 7. The bottom tures at the calibration point 24, and is at flange 8 of the latter engages an exterior least partially volatilized on opposite sides of shoulder 9, while the upper margin of the this point by the heat of the ensuing arc. The shell engages the exterior shoulder 10 on the path of the fuse strip however, is angular, plug body when the shell is screwed fully and in order to follow it the arc must not only home on the spiral rib 6. pass the chilling ledges at the upper margins The open end of the thimble is closed by a of the wells 17 and 18, but must turn abrupt- 35 diaphragm 11 of more or less transparent inly down at each end into these wells. An ansulating material, such as mica, held in place gular path of this sort is inimical to the main by a cap ring 12 resting thereon, having its tenance of the arc. If the bays 15 and 16 are margin 13 spun beneath the head flange 14 filled with insulating material 25 and 26 held at this end of the plug body. in place by the cover 11, the latter adds its 40 Opening from opposite sides of the fuse chilling eflfect to that of the ledges. But

chamber 2 at the open or head end of the plug, whether or not such material is used, I have are bays 15 and 16, with which communicate found that the arc does not become estabthe outer ends of wells 17 and 18 formed in lished, due to the angularity of the path the side wall of the plug body. These bays which it is forced to follow over the chilling 15 and 16 are so shaped as to provide ledges barriers of insulation which form the inner 15, 16 and are shallow so that these ledges walls of the wells 17 and 18.

are relatively close to the outer end of the The construction is economical and efli-,

plug. The well 17 opens at its inner end 19 cient. I have found that fuses of relatively through the wall of the plug to the screw large current carrying capacity can be safely 50 shell contact 7. The well 18 is inclined to the used in a plug of the present construction axis of the plug and opens t ts lnner end o without danger of either establishing an arc the l w r POItIOII 0f the Chamber The between the plug contacts, or of injuring the fuse strip 3 extends transversely across the b d f th l b reason f the heat f the chamber and rests on ledges 15, 16, being are, or excessive pressures of the gases formed 55 thus close to the outer end of the plug and on rupture.

Modifications in detail will readily occur to those skilled in the art which do not depart from the thoughts which underlie what I claim as my invention.

I claim 1. A fuse plug comprising a thimbleshaped insulating body alfording a central chamber, a screw shell side contact mounted on said body, a center contact mounted on said body at the bottom of said chamber, shallow bays opening from substantially opposite sides of said chamber at the outer end thereof and forming ledges, a well opening from one of said bays through the wall of the body to the screw shell, a well opening from the other of said bays through the wall of the body to the inner portion of the chamber, and a fuse strip passing transversely across the chamber at its outer end and restingon said ledges, said strip having one leg ofiset into the well leading. to the screw shell and elec trically connected to the latter, and a second leg ofiset into the well leading to the inner portion of the chamber and passing through said well into said portion of the chamber and there electrically connected to the center contact.

2. A fuse plug comprising a thimbleshaped insulating body affording a central chamber, wells opening through the wall of the body from near the outer end thereof, one well extending to the outside of the body and forming a shoulder where it opens through the outer surface, and one extending to the central chamber, a fuse strip having a transverse portion and off-set legs, the end of one leg being slightly bowed to engage the said shoulder to hold the strip in place in the plug.

In testimony whereof I have signed my name to this specification.

CHARLES nrrrn; 

